From 41cd780524674082b037e7c8461f90c5e42103f0 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 3 Apr 2020 07:20:51 +0000 Subject: [PATCH] uaccess: Selectively open read or write user access When opening user access to only perform reads, only open read access. When opening user access to only perform writes, only open write access. Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/2e73bc57125c2c6ab12a587586a4eed3a47105fc.1585898438.git.christophe.leroy@c-s.fr --- fs/readdir.c | 12 ++++++------ kernel/compat.c | 12 ++++++------ kernel/exit.c | 12 ++++++------ lib/strncpy_from_user.c | 4 ++-- lib/strnlen_user.c | 4 ++-- lib/usercopy.c | 6 +++--- 6 files changed, 25 insertions(+), 25 deletions(-) diff --git a/fs/readdir.c b/fs/readdir.c index de2eceffdee8b..ed6aaad451aa4 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -242,7 +242,7 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, return -EINTR; dirent = buf->current_dir; prev = (void __user *) dirent - prev_reclen; - if (!user_access_begin(prev, reclen + prev_reclen)) + if (!user_write_access_begin(prev, reclen + prev_reclen)) goto efault; /* This might be 'dirent->d_off', but if so it will get overwritten */ @@ -251,14 +251,14 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_access_end(); + user_write_access_end(); buf->current_dir = (void __user *)dirent + reclen; buf->prev_reclen = reclen; buf->count -= reclen; return 0; efault_end: - user_access_end(); + user_write_access_end(); efault: buf->error = -EFAULT; return -EFAULT; @@ -327,7 +327,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return -EINTR; dirent = buf->current_dir; prev = (void __user *)dirent - prev_reclen; - if (!user_access_begin(prev, reclen + prev_reclen)) + if (!user_write_access_begin(prev, reclen + prev_reclen)) goto efault; /* This might be 'dirent->d_off', but if so it will get overwritten */ @@ -336,7 +336,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, &dirent->d_type, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_access_end(); + user_write_access_end(); buf->prev_reclen = reclen; buf->current_dir = (void __user *)dirent + reclen; @@ -344,7 +344,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return 0; efault_end: - user_access_end(); + user_write_access_end(); efault: buf->error = -EFAULT; return -EFAULT; diff --git a/kernel/compat.c b/kernel/compat.c index 843dd17e6078b..b8d2800bb4b71 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -199,7 +199,7 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - if (!user_access_begin(umask, bitmap_size / 8)) + if (!user_read_access_begin(umask, bitmap_size / 8)) return -EFAULT; while (nr_compat_longs > 1) { @@ -211,11 +211,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, } if (nr_compat_longs) unsafe_get_user(*mask, umask++, Efault); - user_access_end(); + user_read_access_end(); return 0; Efault: - user_access_end(); + user_read_access_end(); return -EFAULT; } @@ -228,7 +228,7 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - if (!user_access_begin(umask, bitmap_size / 8)) + if (!user_write_access_begin(umask, bitmap_size / 8)) return -EFAULT; while (nr_compat_longs > 1) { @@ -239,10 +239,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, } if (nr_compat_longs) unsafe_put_user((compat_ulong_t)*mask, umask++, Efault); - user_access_end(); + user_write_access_end(); return 0; Efault: - user_access_end(); + user_write_access_end(); return -EFAULT; } diff --git a/kernel/exit.c b/kernel/exit.c index 389a88cb30819..2d97cbba512db 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1557,7 +1557,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, if (!infop) return err; - if (!user_access_begin(infop, sizeof(*infop))) + if (!user_write_access_begin(infop, sizeof(*infop))) return -EFAULT; unsafe_put_user(signo, &infop->si_signo, Efault); @@ -1566,10 +1566,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, unsafe_put_user(info.pid, &infop->si_pid, Efault); unsafe_put_user(info.uid, &infop->si_uid, Efault); unsafe_put_user(info.status, &infop->si_status, Efault); - user_access_end(); + user_write_access_end(); return err; Efault: - user_access_end(); + user_write_access_end(); return -EFAULT; } @@ -1684,7 +1684,7 @@ COMPAT_SYSCALL_DEFINE5(waitid, if (!infop) return err; - if (!user_access_begin(infop, sizeof(*infop))) + if (!user_write_access_begin(infop, sizeof(*infop))) return -EFAULT; unsafe_put_user(signo, &infop->si_signo, Efault); @@ -1693,10 +1693,10 @@ COMPAT_SYSCALL_DEFINE5(waitid, unsafe_put_user(info.pid, &infop->si_pid, Efault); unsafe_put_user(info.uid, &infop->si_uid, Efault); unsafe_put_user(info.status, &infop->si_status, Efault); - user_access_end(); + user_write_access_end(); return err; Efault: - user_access_end(); + user_write_access_end(); return -EFAULT; } #endif diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index 706020b06617c..b90ec550183ae 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -116,9 +116,9 @@ long strncpy_from_user(char *dst, const char __user *src, long count) kasan_check_write(dst, count); check_object_size(dst, count, false); - if (user_access_begin(src, max)) { + if (user_read_access_begin(src, max)) { retval = do_strncpy_from_user(dst, src, count, max); - user_access_end(); + user_read_access_end(); return retval; } } diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c index 41670d4a58165..1616710b8a82c 100644 --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -109,9 +109,9 @@ long strnlen_user(const char __user *str, long count) if (max > count) max = count; - if (user_access_begin(str, max)) { + if (user_read_access_begin(str, max)) { retval = do_strnlen_user(str, count, max); - user_access_end(); + user_read_access_end(); return retval; } } diff --git a/lib/usercopy.c b/lib/usercopy.c index cbb4d9ec00f20..ca2a697a20618 100644 --- a/lib/usercopy.c +++ b/lib/usercopy.c @@ -58,7 +58,7 @@ int check_zeroed_user(const void __user *from, size_t size) from -= align; size += align; - if (!user_access_begin(from, size)) + if (!user_read_access_begin(from, size)) return -EFAULT; unsafe_get_user(val, (unsigned long __user *) from, err_fault); @@ -79,10 +79,10 @@ int check_zeroed_user(const void __user *from, size_t size) val &= aligned_byte_mask(size); done: - user_access_end(); + user_read_access_end(); return (val == 0); err_fault: - user_access_end(); + user_read_access_end(); return -EFAULT; } EXPORT_SYMBOL(check_zeroed_user); -- 2.30.2